Monitoring of the sciatic nerve during hamstring lengthening by evoked EMG

Area of Science:

• Neurology
• Orthopedic Surgery
• Biomedical Engineering

Background:

• Hamstring lengthening is a common orthopedic procedure for conditions like spastic cerebral palsy.
• Traction injury to the sciatic nerve is a potential complication during hamstring lengthening surgery.
• Assessing sciatic nerve function during the procedure is crucial for preventing iatrogenic injury.

Purpose of the Study:

• To evaluate the impact of hamstring lengthening on sciatic nerve conduction.
• To investigate the utility of evoked electromyography (EMG) in monitoring nerve function during this procedure.
• To identify potential risks and protective measures against sciatic nerve traction injury.

Main Methods:

• Ten children with spastic cerebral palsy underwent bilateral distal hamstring lengthening.
• Evoked electromyography (EMG) potentials of the sciatic nerve were recorded before, during, and after the hamstring lengthening procedure.
• Recordings were taken at various knee flexion angles (90, 60, 30 degrees) and with the hip and knee extended.

Main Results:

• A gradual decrease in evoked EMG amplitude was observed with increasing hamstring lengthening.
• Significant amplitude reduction occurred at 60 degrees (mean 34%) and 30 degrees (mean 86%) of knee flexion.
• EMG amplitude returned to pre-lengthening levels upon hip extension at the procedure's conclusion.

Conclusions:

• Monitoring sciatic nerve evoked EMG during hamstring lengthening can detect conduction changes.
• This monitoring may serve as a valuable tool to prevent traction injuries to the sciatic nerve.
• Intraoperative neurophysiological assessment is recommended for hamstring lengthening procedures.